Hi. Im new here! 
I am currently trying to tag my audiobooks.
I want to have the filename like this: Author - Album 01.
Same title on them all, only with a number after the album.
For example: J. K. Rowling - Harry Potter 1 - Part 01
Or like this: Stephen King - Liseys Story 01
How can I do this as easy as possible?
Have tried to auto numbering the track number, and it worked a couple of times, but now its suddenly impossible to get a 0 first on numbers from 1 - 9. If I write 01 in the track colum, it wount save, and it's back on 1.
What am I doing wrong?
[×] Leading zeros for tracknumbers (01, 02, ...)
Ensure you have that option checked in the autonumbering wizard?
Use CTRL-S to save the changes. Do not accidentally apply tag or track before saving?
Yes, that option is checked, but it still sometimes end up as 1, not 01.
I think this happens if there are only maximum 9 tracks in a folder or the sorting makes MP3tag not see all tracks at a time in a folder.
As an alternative you may apply an action of the type
Format value for TRACK
Format string: $num(%track%,2)
This creates leading zeros were possible.
Please tell us on which filetype does this happen?
For MP4 it is so, ...
because the track tag-field can hold an integer number (e. g. 1) ...
but not a numerical text string (e. g. 01).
DD.20150707.1550.CEST